PS 62-197 - Habitat use of reintroduced fishers with respect to trophic relationships

Thursday, August 10, 2017
Exhibit Hall, Oregon Convention Center
Mitchell A Parsons, School of Environmental and Forest Sciences, University of Washington, Seattle, WA and Laura R. Prugh, School of Environmental & Forest Sciences, University of Washington, Seattle, WA

Fishers (Pekania pennanti) are a species of conservation concern in the western United States and reintroductions have become a common strategy in restoring fishers to their historic range. In winter 2015, Washington Department of Fish and Wildlife and their collaborators began a fisher reintroduction program in the South Cascades of Washington. While habitat use with respect to forest vegetation and structure has been well studied in fishers, little is known about how prey availability and distribution of other carnivores influence fisher habitat use. However, as mesopredators, both these factors likely are important in fisher habitat selection. Our goal was to assess mammalian prey availability and carnivore distributions in the fisher reintroduction area, and how these attributes vary with habitat characteristics and forest management practices. We used small mammal trapping to measure mouse, vole and chipmunk density, index surveys to measure squirrel and hare relative abundance and remote cameras to document carnivore distributions to assess how forest management and habitat characteristics influence prey and carnivore distributions. When combined with telemetry locations from the fisher reintroduction project, these data will allow land managers to develop practices to improve habitat for fishers in the reintroduction area with regard for the trophic relationships of fishers.


Preliminary data suggest that mouse and vole density increases with stand age and woody debris, squirrel abundance increases with elevation and open understory conditions, and snowshoe hare abundance is maximized in young stands with high tree density. These variable responses highlight the need for information on diet of fisher for making management decisions. Occupancy modeling of remote camera data suggests that fishers select for stands with high basal area while coyotes and bobcats negatively responded to increases in average tree diameter. These selection patterns may result in avoidance between fishers and two potential predators in the South Cascades.